A computer log was a diary or archive of events, a form of data, in this case generated by a computer system or systems. In the late 23rd century, Federation starships were equipped with a "black box" that stored computer logs. The logs could be used in criminal investigations or to determine the cause of a lost ship. Computer logs were for official purposes only and were available to authorities only under specific legal circumstances or court order. (TOS: "Court Martial"; Star Trek IV: The Voyage Home)

After Dukat and Kira Nerys captured a Klingon Bird-of-Prey in 2372, they found that the computer logs contained extremely valuable status reports from Klingon starships and outposts throughout the Cardassian Union. (DS9: "Return to Grace")